# CVE-2025-4600: HTTP Request Smuggling in Google Cloud Classic Application Load Balancer due to Improper Chunked Encoding Validation

> Attackers could exploit HTTP request smuggling in Google Cloud Classic Application Load Balancer to misinterpret backend requests, potentially accessing or modifying data.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:L/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 May 2025
- **Updated:** 8 Sep 2025
- **Also known as:** GHSA-crqj-898f-x3m2

## What is CVE-2025-4600?

CVE-2025-4600 is a high-severity vulnerability in Google Cloud Classic Application Load Balancer, published on 16 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A request smuggling vulnerability existed in the Google Cloud Classic Application Load Balancer due to improper handling of chunked-encoded HTTP requests. This allowed attackers to craft requests that could be misinterpreted by backend servers. The issue was fixed by disallowing stray data after a chunk, and is no longer exploitable. No action is required as Classic Application Load Balancer service after 2025-04-26 is not vulnerable.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2025-4600?

It affects 1 product.


Products: Google Application Load Balancer.

## How do I fix CVE-2025-4600?

No fix has been published for CVE-2025-4600 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-4600 being exploited?

There is no known exploitation of CVE-2025-4600 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-4600 and fix it if it is affected.

What it is: CVE-2025-4600 is a high-severity vulnerability in Google Cloud Classic Application Load Balancer, published on 16 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-4600 in the wild and no public exploit code.

Affected product: Google Cloud Classic Application Load Balancer. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-4600/ (Markdown: https://insights.sbomify.com/CVE-2025-4600/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-4600
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-4600
- OSV: https://osv.dev/vulnerability/CVE-2025-4600

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-4600/
Summaries are generated and may contain mistakes; the official description above is the record.